如何在ionic 4中上传图片之前压缩或调整图片大小？

ionic cordova plugin add cordova-plugin-camera

npm install ng2-img-max --save

import { Camera, CameraOptions } from '@ionic-native/camera/ngx';
import { Ng2ImgMaxService } from 'ng2-img-max';

constructor(private camera: Camera, private ng2ImgMax: Ng2ImgMaxService) { }

uploadImage() {
  const options: CameraOptions = {
    quality: 100,
    destinationType: this.camera.DestinationType.FILE_URI,
    sourceType: this.camera.PictureSourceType.PHOTOLIBRARY,
    encodingType: this.camera.EncodingType.JPEG,
    mediaType: this.camera.MediaType.PICTURE
  };

  this.camera.getPicture(options).then((imageData) => {
    // 压缩或调整图片大小
    this.ng2ImgMax.compressImage(imageData, 0.5).subscribe(
      result => {
        // 在这里处理压缩后的图片
        console.log(result);
      },
      error => {
        console.log('Error occurred while compressing image:', error);
      }
    );
  }, (err) => {
    console.log('Error occurred while selecting image:', err);
  });
}